You might find an answer to the most frequently asked questions about syslog-ng here. If not, please notify us.
No. Those daemons fail to notice that the other end ceased to listen to them. Their developer should be notified. In the meantime, you should either restart those daemons when syslog-ng is restarted, or live without their messages. Anyway this behaviour might as well mean that these daemons are broken in other ways too.